The objectives of the proposed research are to study the mechanisms whereby lipids are transported. Two areas of transport will be studied: 1) Dietary cholesterol absorption and uptake by tissues, and 2) phospholipid transport within and between cells. For project #1, the emphasis will be on a) improvement of methodology for cholesterol absorption, and b) study of the fate of serum cholesterol present in chylomicron remnants. For project #2, phospholipid exchange proteins will be purified from several tissues. These will be used to study membrane phospholipid asymmetry and flip-flop.